Numerous questionnairs have been used in an attempt to assess the physicl activity profile of the general population and relate characteristics of their activity to current or future health status. A major methodological difficulty of these studies has been the lack of a readily available technique to validate responses to the questionnaires. We propose that the simultaneous recording of heart rate and body movement using a Vitalog monitor will provide more accurate information on the physical activity profile of free-living persons than other available procedures and that the results of these recordings can be used as a standard for determining the validity of physical activity questionnaires for use in large-scale investigations. Studies will be conducted to determine the ability of combined heart rate and motion sensor recordings to quantify the energy cost of physical activity in the laboratory and during usual living situations. In 24 men and women heart rate and motion sensor recordings will be compared to measured oxygen uptake during activities of different types and intensities. Comparisons will also be made between the direct observation of activities on-the-job, at-home and during leisure-time and the simultaneous recording of heart rate and body movement in 48 men and women. These data will allow us to develop an algorithm for the simultaneous analysis of heart rate and body movement that should effectively quantify most activity that causes a significant increase in energy expenditure. The variability of heart rate and motion sensor recordings and responses to selected physical activity questionnaires will be determined over one year in 120 adults and the validity of the questionnaires will be determined using combined heart rate and motion sensor recordings as a standard. Vitalog recordings for 3 consecutive days, 7-day activity recall questionnaire and a 3-month activity questionnaire will be obtained quarterly. The Minnesota Leisure-Time Physical Activity Questionnaire will be administered at the beginning and end of the year as will a maximal exercise test and tests of blood lipoproteins, blood pressure and body composition. Analysis will be performed to determine which indicators of activity during the year best relate to thest measures of cardiovascular health/fitness.